Diagram of a DNA-membrane complex, a material formed by mixing negatively charged DNA molecules with positively charged artificial versions of the membranes that form the protective coverings of cells. Such complexes, which are presently used as delivery vehicles in gene therapy, have a highly organized internal structure, which gives them many potential technological applications.
The purple and blue ribbons represent the DNA double helices, which form a one-dimensional lattice between a double-layer sheet of the membrane. The green and white spheres represent the hydrophilic ("water-loving") ends of the charged and neutral molecules that respectively make up the membrane. The yellow chains (two to each sphere) represent the hydrophobic ("water-fearing") hydrocarbon "tails" in the molecules.
Using a 1-by-4 micron x-ray beam at the Advanced Photon Source at Argonne National Lab near Chicago, Illinois, a UC-Santa Barbara-Argonne team has shown that these materials are molecularly aligned at mesoscopic length-scales (microns). The spaces between the DNA molecules can be tuned from 2.5-6.0 nm. Since the nanoporous structure of these DNA-membrane complexes is locally aligned, these materials can have novel technological applications, such as electrophoretic media for sorting molecules or as templates for the fabrication of inorganic nanostructures with sizes and geometries that were previously impossible to attain.
Gerard C. L. Wong, Youli Li, Ilya Koltover, Cyrus R. Safinya, Zhonghou Cai, and Wenbing Yun in the October 5, 1998 issue of Applied Physics Letters.
Joachim O. Rädler, Ilya Koltover, Tim Salditt, and Cyrus R. Safinya, Science, 275: 810-814 (7 February 1997).
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